IPAbuseCheck offers a simple lookup which checks an IP address against Zscaler’s database of 20,000 addresses detected by the company as having been used for abuse since the company started recording such attacks in July.

The service has some obvious limitations starting with the fact that it is only Zscaler’s database of abusive IPs that addresses will be checked against; the database is only a few months old but its usefulness should increase with time. The company also admits there could be some false positives.

However, an advantage is that is that unlike some IP blacklists it can more reliably record the real IP address of the abusive PC or server before the traffic is hidden behind a proxy. Sometimes this can catch surprising victims that have had their own servers hijacked to act as open proxies.